diff --git a/crates/ra_macros/src/lib.rs b/crates/ra_macros/src/lib.rs
index 8c284fa719c..9485b1c3db6 100644
--- a/crates/ra_macros/src/lib.rs
+++ b/crates/ra_macros/src/lib.rs
@@ -13,3 +13,4 @@ macro_rules! impl_froms {
 pub mod tt;
 pub mod mbe;
 mod mbe_parser;
+mod mbe_expander;
diff --git a/crates/ra_macros/src/mbe.rs b/crates/ra_macros/src/mbe.rs
index 72d6707aa12..ec811c5f0bf 100644
--- a/crates/ra_macros/src/mbe.rs
+++ b/crates/ra_macros/src/mbe.rs
@@ -2,7 +2,10 @@ use smol_str::SmolStr;
 
 use crate::tt::{self, Delimiter};
 
-pub use crate::mbe_parser::parse;
+pub use crate::{
+    mbe_parser::parse,
+    mbe_expander::exapnd,
+};
 
 #[derive(Debug)]
 pub struct MacroRules {
diff --git a/crates/ra_macros/src/mbe_expander.rs b/crates/ra_macros/src/mbe_expander.rs
new file mode 100644
index 00000000000..42622965951
--- /dev/null
+++ b/crates/ra_macros/src/mbe_expander.rs
@@ -0,0 +1,5 @@
+use crate::{mbe, tt};
+
+pub fn exapnd(rules: &mbe::MacroRules, input: tt::Subtree) -> Option<tt::Subtree> {
+    Some(input)
+}